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Oceanography
Lesson 5: Shoreline
Erosion (Where's the
Beach?)
Grade Level: 8th
Subject: Science
and Math
Learner Outcomes:
- Realize that
the forces of nature are constant, unrelenting and immediate.
- Understand
the erosional and depositional processes that occur along coastlines and
the causes of each.
- Recognize
and explain the formation of various coastline features.
- Compare the
effects of waves vs. longshore currents on shorelines.
- Understand
the different methods of controlling coastal erosion and the pros and cons
of implementing each one.
- Practice
making contour maps and use math to figure rates of erosion, to work with
size scales and to create charts and graphs.
- Become aware
of some of the dangers of swimming in unfamiliar coastal areas and learn
how recognize and avoid rip currents..
Duration of Lesson:
2-5 45 minute class periods
Materials per group:
- Stream
table with clamp for outflow
- Water
- Graph paper
- Plexiglas
sheets or heavy clear plastic sheets
- Rocks, pebbles,
sticks, etc. to build erosion prevention structures 6. Sand
- Stop watch
- Grease pencils
or markers in red & black
- "Wave generator"
- Salt (for enrichment
activity)
Technology tools/Courseware:
- Calculator,
preferably with graphing capabilities
- Computer
with internet connection (optional)
- Computer
printer (optional)
Teacher Notes:
- I recommend
that the plexiglas sheets cover about 2/3 of the length of the stream table.
This allows plenty of open space to generate waves and still have plenty
of room to record the contours at the beach end. Also, I have found
that a 1 inch grid on the plexiglas works very well. This can easily
be translated to 1/4" or 1/2" grids on graph paper.
- I always
do this lab outside to avoid the inevitable messes that occur during the
activity. Also, I can just dump the sand and rinse the stream tables
before bringing them back inside.
- Mark a grid
on the underside of the plexiglas or plastic so that it will not be erased
when the marks are erased from each simulation.
- I use small
rectangles of ceramic tile to represent the various jetties, seawalls,
etc.
- The "wave
generator" is simply a flat piece of wood that can be used by the students
to create their waves.
- Have students
practice with the "wave generator" until they are able to produce reasonably
uniform wave action.
- Point out
the various formations as they appear, as they will change as each simulation
progresses. Point out places where rip currents are likely to form,
explain the implications to swimmers and how to avoid being dragged out
to sea and drowned by these. (First by avoiding it, or if that is not possible,
by swimming across the current rather than against it.) Make sure they
all recognize places where these extremely dangerous currents are likely
to be found.
- Repeatedly
remind students that these are fairly accurate simulations in miniature
of actions that are actually happening every day along our coastlines.
Procedures:
Part A:
- Set up stream
table by building a gently sloping beach in one end and adding water to
the other end.
- Tape the
plexiglas grid onto the top of the stream table with the prepared grid
side down toward the water.
- Mark the
contours of the beach on the top of the plexiglas with the black marker
to show the original position of the beach.
- Have one
student make waves for 2 minutes, timed by another student. Stop
and use a red marker to trace the new beach contour on the plexiglas.
- Repeat step
4 several more times, recording the changes in the beach contours after
each 2 minute interval.
- Transpose
the patterns of contour changes to graph paper by changing the scale from
plexiglas grid to graph grid.
- Use calculator
to determine the rate of erosion of each trial and graph results.
Part B:
- Rebuild
the beach to match the original contour.
- Repeat steps
2-7 above with much more vigorous wave action to simulate storm damage.
- Compare and
contrast normal and storm erosion.
Part C:
- Design and
create simulations to show the effects of various methods of erosion control
along sandy beaches. (Jetties, groins, seawalls can be made from
rocks, ceramic tile, or clay. Riprap can be made using gravel.
Barrier islands can be made from additional sand)
- Repeat the
steps 2-7 from Part A.
- Determine
the most effective methods of erosion control.
Part D:
- Set up a
simulation in which the beach is located along the side of the stream table
so that the currents will appear as longshore currents rather than as waves
hitting the beach straight on.
- Create an
inlet and simulate the effect of the longshore current on it. Again
use markers to show the contours of the beach on the plexiglas cover and
the effects of the currents at regular intervals. Transfer these
results to graph paper.
- Recreate
the inlet and add jetties to attempt to protect it from erosion.
Record the effects on the plexiglas and transfer them to graph paper.
Modifications:
- Stream tables
can be made by lining the tops of paper boxes with plastic. Good
results can be had by taping two box tops together end to end.
- Heavy clear
plastic can be substituted for the Plexiglas by being stretched across
the top of the stream table and taped tightly to the sides. This
has the advantage of students being able to remove the plastic without
losing the data recorded on it. This is particularly handy if another
class follows immediately and must use the same stream tables.
- Repeat the
simulation using sand with different sizes of grains or by mixing some
very fine sand in with larger grains of a different color or texture.
Watch for formation of lines of "heavies" (bands caused by the deposition
of sand according to differences in mass of its particles).
Enrichment Activities:
- Create beach
scenes in sizes proportional to actual sizes to represent such things
as homes, lighthouses, people, trees, etc. and describe what happens to
them in normal and storm simulations.
- Set up hypotheses
and design experiments to show erosion along various types of coastlines.
(Use rocks, tiles, gravel, etc. to form a rocky coastline and simulate
erosional patterns for that type of coastal area.)
- Design and
perform simulations to show how various coastal geological formations such
as sea arches, stacks, offshore bars, spits, etc. are formed by wave actions.
- Observe the
creation of a delta by using a stream of fresh water to simulate a river
and having it flow through sand or soil into the ocean (a saturated salt
water solution).
- Set up a
debate between "fishermen" who want jetties built to protect their inlet
and "conservationists" who are afraid that the jetties, if built, will
destroy wildlife habitats and wetlands as well as cause extreme erosion
of beaches along the coast. Before doing this, I recommend that students
see the VCR tape "The Challenge On The Coasts" (of the Conserving America
series).
- Explore local
vicinity to look for erosional problems caused by water and decide how
they might be addressed.
Evaluation/Assessment:
Subjective:
- Observation
- Informal
questions and answers
- Class and
group discussion
Objective:
- Test on terminology
and concepts
- Grade graphs
and diagrams by using a rubric
- Grade written
reports from each group
West
Virginia State Instructional Goals and Objectives:
Science/Math: 8.1, 8.2, 8.3, 8.5,
8.6, 8.7, 8.8, 8.9, 8.10, 8.11, 8.12, 8.13, 8.14, 8.15, 8.16, 8.17, 8.18,
8.19, 8.20, 8.21, 8.22, 8.23, 8.24, 8.25, 8.26, 8.27, 8.54, 8.70, 8.84,
8.89, 8.96 8.9, 8.10, 8.11, 8.18, 8.26, 8.40, 8.44, 8.50
National
Standards:
Science:
- Understands Earth's
composition and structure
- Knows that
the Earth is comprised of layers including a core, mantle, lithosphere,
hydrosphere, and atmosphere
- Knows how
land forms are created through a combination of constructive and destructive
forces (e.g., constructive forces such as crustal deformation, volcanic
eruptions, and deposition of sediment; destructive forces such as weathering
and erosion)
- Understands the nature
of scientific knowledge
- Understands
the nature of scientific explanations (e.g., use of logically consistent
arguments; emphasis on evidence; use of scientific principles, models and
theories; acceptance or displacement of explanations based on new scientific
evidence)
-
Understands the nature
of scientific inquiry
- Knows that
there is no fixed procedure called "the scientific method", but that
investigations involve systematic observations, carefully collected, relevant
evidence, logical reasoning, and some imagination in developing hypotheses
and explanations
- Designs and
conducts a scientific investigation (e.g., formulates hypotheses, designs
and executes investigations, interprets data, synthesizes evidence into
explanations, proposes alternative explanations for observations, critiques
explanations and procedures)
- Knows that
observations can be affected by bias (e.g., strong beliefs about what should
happen in particular circumstances can prevent the detection of other results)
- Establishes
relationships based on evidence and logical argument (e.g., provides causes
for effects)
Math:
-
Uses a variety of
strategies in the problem-solving process
- Represents
problem situations in and translates among oral, written, concrete, pictorial,
and graphical forms
- Generalizes
from a pattern of observations made in particular cases, makes conjectures,
and provides supporting arguments for these conjectures (i.e., uses inductive
reasoning)
- Uses a variety
of reasoning processes (e.g., reasoning from a counter example, using proportionality)
to model and to solve problems
- Understands and applies
basic and advanced properties of the concepts of measurement
- Selects and
uses appropriate units and tools, depending on degree of accuracy required,
to find measurements for real-world problems
- Understands the general
nature and uses of mathematics
- Understands
that mathematics has been helpful in practical ways for many centuries
- Understands
that mathematicians often represent real things using abstract ideas like
numbers or lines: they then work with these abstractions to learn
about the things they represent
Job/Career Clusters:
- Science/Natural Resources
- Engineering/Technical
References:
- For the film: "Challenge
On The Coast" (Conserving America series)
Teacher's Video Company
1-800-262-8837 for catalog and to order
- For Career information:
- For severity of U.S.
coastal erosion problems:
- For coastal erosion
field trip:
Authors: Bryan
Barnett, Pat
Ryan and Judy
Staats
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